Merge #719

719: Add --list to known subcommands. r=Alexhuszagh a=Alexhuszagh

`cross --list` should list the subcommands present for cargo in the image, rather on the host. This works because any option provided before a subcommand has priority over the subcommand. For example, `cargo build --help` prints the help menu for `cargo build`, but `cargo --help build` ignores `build` and prints the help for `cargo`. Therefore, the options `--help`, `--version`, and `--list` can be treated as pseudo-subcommands.

Fixes #715.

Co-authored-by: Alex Huszagh <ahuszagh@gmail.com>

CHANGELOG.md

@@ -7,7 +7,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 - #722 - boolean environment variables are evaluated as truthy or falsey.
 - #721 - add support for running doctests on nightly if `CROSS_UNSTABLE_ENABLE_DOCTESTS=true`.
-- #719 - add android runner to preload `libc++_shared.so`.
+- #720 - add android runner to preload `libc++_shared.so`.
+- #719 - add `--list` to known subcommands.
 - #718 - remove deb subcommand.
 - #714 - use host target directory when falling back to host cargo.
 - #713 - convert relative target directories to absolute paths.

src/cargo.rs

@@ -17,11 +17,12 @@ pub enum Subcommand {
     Bench,
     Clippy,
     Metadata,
+    List,
 }
 
 impl Subcommand {
     pub fn needs_docker(self) -> bool {
-        !matches!(self, Subcommand::Other)
+        !matches!(self, Subcommand::Other | Subcommand::List)
     }
 
     pub fn needs_interpreter(self) -> bool {
@@ -45,6 +46,7 @@ impl<'a> From<&'a str> for Subcommand {
             "bench" => Subcommand::Bench,
             "clippy" => Subcommand::Clippy,
             "metadata" => Subcommand::Metadata,
+            "--list" => Subcommand::List,
             _ => Subcommand::Other,
         }
     }
@@ -88,3 +90,8 @@ pub fn root() -> Result<Option<Root>> {
 pub fn run(args: &[String], verbose: bool) -> Result<ExitStatus> {
     Command::new("cargo").args(args).run_and_get_status(verbose)
 }
+
+/// run cargo and get the output, does not check the exit status
+pub fn run_and_get_output(args: &[String], verbose: bool) -> Result<std::process::Output> {
+    Command::new("cargo").args(args).run_and_get_output(verbose)
+}

src/cli.rs

@@ -36,6 +36,39 @@ fn bool_from_envvar(envvar: &str) -> bool {
     }
 }
 
+pub fn is_subcommand_list(stdout: &str) -> bool {
+    stdout.starts_with("Installed Commands:")
+}
+
+pub fn group_subcommands(stdout: &str) -> (Vec<&str>, Vec<&str>) {
+    let mut cross = vec![];
+    let mut host = vec![];
+    for line in stdout.lines().skip(1) {
+        // trim all whitespace, then grab the command name
+        let first = line.trim().split_whitespace().next();
+        if let Some(command) = first {
+            match Subcommand::from(command) {
+                Subcommand::Other => host.push(line),
+                _ => cross.push(line),
+            }
+        }
+    }
+
+    (cross, host)
+}
+
+pub fn fmt_subcommands(stdout: &str) {
+    let (cross, host) = group_subcommands(stdout);
+    if !cross.is_empty() {
+        println!("Cross Commands:");
+        cross.iter().for_each(|line| println!("{}", line));
+    }
+    if !host.is_empty() {
+        println!("Host Commands:");
+        host.iter().for_each(|line| println!("{}", line));
+    }
+}
+
 pub fn parse(target_list: &TargetList) -> Result<Args> {
     let mut channel = None;
     let mut target = None;
@@ -74,7 +107,7 @@ pub fn parse(target_list: &TargetList) -> Result<Args> {
                     all.push("--target-dir=/target".into());
                 }
             } else {
-                if !arg.starts_with('-') && sc.is_none() {
+                if (!arg.starts_with('-') || arg == "--list") && sc.is_none() {
                     sc = Some(Subcommand::from(arg.as_ref()));
                 }
 

src/extensions.rs

@@ -10,6 +10,7 @@ pub trait CommandExt {
     fn run(&mut self, verbose: bool) -> Result<()>;
     fn run_and_get_status(&mut self, verbose: bool) -> Result<ExitStatus>;
     fn run_and_get_stdout(&mut self, verbose: bool) -> Result<String>;
+    fn run_and_get_output(&mut self, verbose: bool) -> Result<std::process::Output>;
 }
 
 impl CommandExt for Command {
@@ -42,14 +43,32 @@ impl CommandExt for Command {
 
     /// Runs the command to completion and returns its stdout
     fn run_and_get_stdout(&mut self, verbose: bool) -> Result<String> {
+        let out = self.run_and_get_output(verbose)?;
+        self.status_result(out.status)?;
+        out.stdout()
+    }
+
+    /// Runs the command to completion and returns the status and its [output](std::process::Output).
+    ///
+    /// # Notes
+    ///
+    /// This command does not check the status.
+    fn run_and_get_output(&mut self, verbose: bool) -> Result<std::process::Output> {
         self.print_verbose(verbose);
-        let out = self
-            .output()
-            .wrap_err_with(|| format!("couldn't execute `{:?}`", self))?;
+        self.output()
+            .wrap_err_with(|| format!("couldn't execute `{:?}`", self))
+            .map_err(Into::into)
+    }
+}
 
-        self.status_result(out.status)?;
+pub trait OutputExt {
+    fn stdout(&self) -> Result<String>;
+}
 
-        String::from_utf8(out.stdout).wrap_err_with(|| format!("`{:?}` output was not UTF-8", self))
+impl OutputExt for std::process::Output {
+    fn stdout(&self) -> Result<String> {
+        String::from_utf8(self.stdout.clone())
+            .wrap_err_with(|| format!("`{:?}` output was not UTF-8", self))
     }
 }
 

src/main.rs

@@ -17,6 +17,7 @@ mod rustc;
 mod rustup;
 
 use std::env;
+use std::io::{self, Write};
 use std::path::PathBuf;
 use std::process::ExitStatus;
 
@@ -27,6 +28,7 @@ use serde::Deserialize;
 use self::cargo::{Root, Subcommand};
 use self::cross_toml::CrossToml;
 use self::errors::*;
+use self::extensions::OutputExt;
 use self::rustc::{TargetList, VersionMetaExt};
 
 #[allow(non_camel_case_types)]
@@ -420,11 +422,25 @@ fn run() -> Result<ExitStatus> {
         }
     }
 
-    eprintln!("Warning: Falling back to `cargo` on the host.");
-
     // if we fallback to the host cargo, use the same invocation that was made to cross
     let argv: Vec<String> = env::args().skip(1).collect();
-    cargo::run(&argv, verbose)
+    eprintln!("Warning: Falling back to `cargo` on the host.");
+    match args.subcommand {
+        Some(Subcommand::List) => {
+            // this won't print in order if we have both stdout and stderr.
+            let out = cargo::run_and_get_output(&argv, verbose)?;
+            let stdout = out.stdout()?;
+            if out.status.success() && cli::is_subcommand_list(&stdout) {
+                cli::fmt_subcommands(&stdout);
+            } else {
+                // Not a list subcommand, which can happen with weird edge-cases.
+                print!("{}", stdout);
+                io::stdout().flush().unwrap();
+            }
+            Ok(out.status)
+        }
+        _ => cargo::run(&argv, verbose),
+    }
 }
 
 #[derive(PartialEq, Debug)]